Percutaneous interventions are now the primary means of managing coronary artery disease, where over one million procedures, including over 500,000 coronary stents, were performed during 1999. Despite these advances, restenosis continues to be a major limitation of percutaneous coronary revascularization procedures. Even in the best cardiac catheterization labs between 10-20 percent of treated lesions must be revascularized. Intravascular ultrasound (IVUS) is routinely used in many of these laboratories to guide procedures. Although image quality has improved steadily, still only about 7-8 percent of total procedures use this technology. The primary reason for this low rate is that an IVUS study can add appreciable time to a procedure without significantly improving the outcome. This will change only when IVUS can efficiently guide interventions with improved outcomes. The long range goal of this research program remains to manage nearly every aspect of coronary artery interventions with intravascular ultrasound (IVUS). It focuses on the common mechanical interventions of balloon angioplasty (PCTA) and endovascular stenting. However, the methods are general and can apply to other procedures such as ablation/vaporization and brachytherapy. Based on progress during the initial funding period, it now appears that IVUS can provide key information about anatomical and elastic properties of the artery wall flow and flow dynamics within the lumen. Given these developments, an ambitious research plan has been developed to address how IVUS can help manage nearly every aspect of coronary artery interventions. For the mechanical interventions of balloon angioplasty and endovascular stenting, the applicants hypothesize that IVUS can identify the mechanical properties of arterial lesions, guide and monitor both PCTA and stent deployment to minimize tissue injury while insuring full stent extensions, assess flow dynamics pre- and post-interventions, and determine the likelihood of restenosis. In addition, an integrated IVUS delivery will be constructed to perform mechanical interventions under full ultrasound guidance, including real-time elasticity and flow monitoring. Such a catheter is key to optimizing stent deployment while minimizing tissue injury and subsequent restenosis. In addition, an integrated device can dramatically reduce the number of catheters employed during a typical procedure.